A light curtain in an elevator comprises two opposite vertical detectors at a horizontal distance from each other. One detector comprises a transmitter and the other detector comprises a receiver. The transmitter comprises a number of light emitting diodes emitting infrared light which is directed with a lens system towards the opposite receiver. When an object enters the region between the transmitter and the receiver some of the infrared beams sent by the transmitter will be obscured. The receiver will detect that some infrared beams are missing and this will activate a safety function which will prevent the closing of the door panels. The light curtain functions thus as a safety device preventing people and goods from being pressed between the door panels when the door panels are to be closed. The door panels will close automatically when a certain time has passed after they have opened unless the light curtain prevents closing of the door panels.
A sliding door construction in an elevator comprises a horizontal railing, a horizontal sill and at least one door panel. The upper end of the at least one door panel is supported with rolls at the railing and the lower end of the at least one door panel is supported with gliding means at the sill. There are centre opening door constructions and side opening door constructions. In a centre opening door construction the door panels on both sides of the centre of the door construction move in opposite directions. In a side door construction the door panels move in the same direction.
In a centre opening door construction, the first detector (transmitter or receiver) and the second detector (receiver of transmitter) are positioned at opposite outer ends of the railing and the sill so that the first detector and the second detector face towards each other. The fixing arrangement in prior art solutions comprises an L-shaped vertically extending support profile. The upper end of the support profile is attached with a bracket and a screw to the railing and the lower end of the support profile is attached in a corresponding way with a bracket and a screw to the sill. The first detector and the second detector are attached to the plane surface of the respective support profile with screws.
The vertically between the railing and the sill extending support profile becomes rather long. The support profile is thus problematic to pack together with the other equipment in the door construction. When the vertical support profile is made of one piece it suits only one door height. Vertical support profiles of different length must thus be kept in stock to suit different door heights. There are also solutions where the vertical support profile is made of two separate pieces. The two separate pieces are then attached to each other with pop-rivets at the installation site. This will cause a longer installation time and a risk of installation mistakes.
Holes are needed in the transmitter and the receiver in order for the screws to pass through the transmitter and the receiver when the transmitter and the receiver are attached to the vertical support profile. These holes in the transmitter and the receiver will decrease the IP-class of the light curtain.
In a side opening door construction, the first detector (transmitter or receiver) can be attached in the same way as in a centre opening door construction to the end of the railing and to the end of the sill at that end of the door construction towards which the door panel opens. The fixing of the second detector (receiver or transmitter) is in a prior art solution done to the slam post against which the door panel closes. The second detector is attached from the upper end and the lower end with a screw and a clamp to the slam post.
The light curtain has also been attached to the door panels in prior art solutions. The detector is in some prior art solutions positioned between an inner profile and a fixing plate. The whole package is then fastened with screws passing through the package to the inner surface of the door panel. The transmitter and the receiver is positioned against each other at the inner surface of the door panels at the opposite edges of the door panels in a centre opening door construction. In a side opening door construction the second detector would have to be fastened to the slam post against which the door panel closes. The second detector could be pre-installed at the door factory to the slam post so that the detector is flush mounted with the surface of the slam post. The edge of the door panel would thus close against the detector. The other possibility is to install the detector to the inner surface of the slam post, said inner surface being parallel with the door panel.
Prior art solutions in which the light curtain is attached to the door panels involve a risk that screw-heads cause scratches to the door panels. Prior art solutions require holes in the transmitter and the receiver in order for the fastening screws to pass through the transmitter and the receiver. These holes in the transmitter and the receiver will decrease the IP-class of the light curtain. Maintenance and replacement of a light curtain fastened with screws and/or brackets and/or clamps means that the screws and/or the brackets and/or the clamps have to be disassembled in order to be able to maintenance or replace the light curtain.